Browse Prior Art Database

OPTICAL TECHNIQUES FOR MONITORING SCAN SYSTEM VELOCITIES

IP.com Disclosure Number: IPCOM000024368D
Original Publication Date: 1980-Jun-30
Included in the Prior Art Database: 2004-Apr-02
Document File: 2 page(s) / 127K

Publishing Venue

Xerox Disclosure Journal

Abstract

In the figure, a simplified view of an optical system for a xerographic copier is shown. In this system, lens 2 produces a line image 3 on drum 4, and the total image is recorded by utilizing a one-dimensional scan. This is performed by linearly translating platen 5 at a velocity v as indicated and rotating the drum in the direction indicated such that its surface has the same tangential velocity. In this system, the relative velocity between the platen and drum must be maintained to avoid image degradation. It is proposed that the relative motion can be measured to a high degree of accuracy and therefore, controlled by monitoring the moire beat frequency between a grating 6 on the platen and a grating 8 on the drum. The gratings shown are black bars printed on a highly reflective support material. Light from the illumination source (not shown) would be reflected from grating 6, imaged through lens 2 onto beam splitter 10 and then focused by lens 12 onto a photodetector array 14. A correction signal is generated which will vary the speed of the rotor 16 to compensate for detected relative velocity differences.

This text was extracted from a PDF file.
At least one non-text object (such as an image or picture) has been suppressed.
This is the abbreviated version, containing approximately 57% of the total text.

Page 1 of 2

XEROX DISCLOSURE JOURNAL

OPTICAL TECHNIQUES FOR MONITORING SCAN SYSTEh4 VELOCITIES
Charles J. Kramer

Proposed Classification
U.S. C1. 355/8 Int. C1. G03g 15/28

Volume 5 Number 3 May/June 1980 279

[This page contains 1 picture or other non-text object]

Page 2 of 2

OPTICAL TECHMQUES FOR MONITORING SCAN SYSTEM VELOCITIES (Cont'd)

In the figure, a simplified view of an optical system for a xerographic copier is shown. In this system, lens 2 produces a line image 3 on drum 4, and the total image is recorded by utilizing a one-dimensional scan. This is performed by linearly translating platen 5 at a velocity v as indicated and rotating the drum in the direction indicated such that its surface has the same tangential velocity. In this system, the relative velocity between the platen and drum must be maintained to avoid image degradation. It is proposed that the relative motion can be measured to a high degree of accuracy and therefore, controlled by monitoring the moire beat frequency between a grating 6 on the platen and a grating 8 on the drum. The gratings shown are black bars printed on a highly reflective support material. Light from the illumination source (not shown) would be reflected from grating 6, imaged through lens 2 onto beam splitter 10 and then focused by lens 12 onto a photodetector array 14. A correction signal is generated which will vary the speed of the rotor 16 to compensate for detected relative velocity differences.

Instead of the reflective grating on the drum, a transmission-type grating could be used. Tie advantage of a reflective grating is that if it printed on a flexible support material, it could be attached to any xerographic drum and therefore, be inexpensive to implement. A second advantage is that if the support material is thin, the motion of the grating corresponds directly to the motion of the drum surface. be to have the grating on a rigid ring (opaque or transparent) the same size as the drum and attach it to the end of the drum. Differences in grating size due to magnification in the imaging system can be compensated for by including additional lenses into the light path at the position indicated by the dashed line in the figure.

An alternative approach would

The proposed technique eliminates the need to keep an accurate count of fringes since what is being...